This invention relates to nonslip, low-cost, initially flat web cores which substantially reduce fabrication, shipping and storage costs and are adapted for use with winding mandrels wherein elongated webs of ribbon or tape materials are wound thereabout to produce finished rolls. More particularly, it is concerned with web cores which include bendable tongues thereon adapted for insertion within an axial slot on the winding mandrel for precluding rotational slippage of the core relative to the mandrel.
In the production of finished rolls of ribbons, adhesive tapes or label stocks and the like, it is a common practice to employ apparatus for simultaneously producing a number of small finished rolls from a large master supply thereof. For example, in the production of rolls of adhesive tape for individual use, a master roll is utilized and individual roll portions are produced by successively slitting the width thereof into a plurality of relatively narrow webs followed by winding on the latter onto individual web cores. In these procedures, individual web cores are conventionally attached to high-speed rotatable winding mandrels and the elongated webs are attached thereto to produce the finished rolls.
The most common web cores heretofore available have consisted simply of cylindrical segments of thin cardboard or plastic which are adapted to be slipped onto an appropriate mandrel for winding of tape or other material therearound. However, in practice it has been discovered that the use of these cylindrical members present a number of serious and heretofore unsolved problems.
One objectionable feature of almost all prior web cores stems from the fact that it is exceedingly difficult to insure a non-slip fit between the core and the winding mandrel. In many instances, workers in the art have resorted to the use of air expandable or hydraulic mandrels, or mandrels having mechanical expansion means such as radially shiftable core engaging teeth in an attempt to obviate this problem. Such devices can be radially expanded as desired after the core is installed thereon in order to hold the latter in its proper position. As can be appreciated however, such complicated apparatus is extremely costly to purchase and use and is time consuming to manipulate. The worker must first position the cylindrical web core on the mandrel in proper alignment therewith and subsequently insure a non-slip fit therebetween by operation of the expanding mechanism associated with the mandrel. This in many cases requires considerable skill, since if the core is too loose on the one hand relative rotative slippage thereof will occur while on the other hand if the mandrel itself is expanded beyond the limits of the circumscribing core, the latter can be torn or otherwise damaged.
An equally important problem associated with the prior cores results from the fact that they were extremely costly to ship and store. By virtue of their cylindrical configuration, they required considerable space while nevertheless being relatively light in weight. Accordingly, due to the large bulk of these cores, the shipping and storage charges associated therewith oftentimes exceeded the actual production costs thereof. Moreover, these problems were compounded because of the necessity of stocking a large inventory of cores of different sizes and widths, which of course materially increased the cost to those utilizing web cores of this type.
In an attempt to overcome the foregoing problems, it has been suggested to employ initially flat web core blanks which can be wrapped about a mandrel and attached thereto to provide the requisite core. In general however, these prior flat core blanks have found little acceptance in the art because of their inability to overcome the problems associated with core slippage. Additionally, the resultant cores were objectionable because there was no way to interconnect the distal ends thereof on the mandrel while nevertheless maintaining a substantially smooth, uninterrupted and continuous arcuate winding surface. That is, use of many of these core blanks required that the ends thereof be overlapped and interconnected by means of complemental tongue and slot structure or the like which of necessity created a bulge or projection along the arcuate surface of the resultant core. As can be appreciated, when an elongated web of material was wound thereabout, the finished roll likewise exhibited an irregular projection thereon by virtue of the underlying irregularity on the web core itself.
Finally, because of the lack of resilience in prior web cores, if they become bent or misshapen (either during shipping or after a web is wound thereabout) there was no practical way to reuse the core. This is particularly significant in cases where intermediate rewindings occur between the master roll and final product. In cases where an intermediate roll core becomes distorted, it is often necessary to discard the entire roll of material since there is no acceptable method of effecting a further rewind thereof. As can be appreciated, this can be an extremely costly problem to the commercial fabricator of finished roll materials. These problems are further compounded by virtue of the fact that the mandrels commonly in use have no mechanical adaptor or the like which permits use of partially misshapen web cores. Thus, if a core does not remain essentially perfect during shipping, storage and initial rewindings, it can become useless and even be the cause of significant commercial losses.
Therefore, there is a need in the art for a lowcost, flexible resilient web core blank that is easily and quickly installable on a winding mandrel without resort to complicated apparatus, is initially flat for ease of storage and shipping, and which effectively avoids problems associated with core slippage while maintaining a smooth, continuous uninterrupted winding surface when installed upon a rotatable mandrel.